The Recruitment/Screening core will oversee recmitment and screening of eligible participants for all of the human subjects studies of the center (Projects 1-3). To accomplish this goal, we will utilize our established recruitment/screening infrastructure, which comprises: 1) an advertising system entailing television, radio, internet and other media; 2) a centralized telephone call answering center that: a) provides initial telephone screening of interested smokers who respond to recruitment advertisements; and b) schedules in-person medical screening sessions; and 3) a physician and three physician assistants covering our four clinical research sites, who conduct physical examinations and additional medical evaluations to implement study inclusion/exclusion criteria. Based on previous experience, this core will be able to recruit, screen and refer to the respective center project approximately 150 participants per year. This participant flow will be more than adequate to help ensure the successful completion of all human studies proposed in this application.